From 2b71ad716b958990603452fd08735bb4ca29953d Mon Sep 17 00:00:00 2001
From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Sun, 17 Dec 2023 22:24:13 +0000
Subject: [PATCH] add first cut at parallel maxloc, adding random tests

---
 src/openpower/decoder/isa/maxloc.py | 43 +++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/src/openpower/decoder/isa/maxloc.py b/src/openpower/decoder/isa/maxloc.py
index 83d89569..73553743 100644
--- a/src/openpower/decoder/isa/maxloc.py
+++ b/src/openpower/decoder/isa/maxloc.py
@@ -3,6 +3,8 @@
 # License: LGPLv3+
 # https://bugs.libre-soc.org/show_bug.cgi?id=676#c2
 
+from random import randint
+
 def m2(a):
     m = 0;
     nm = 0;
@@ -20,6 +22,36 @@ def m2(a):
             i += 1
     return nm;
 
+def sv_maxu(gpr, CR, vl, ra, rb, rt):
+    i = 0
+    while i < vl:
+        CR[0] = cmpd(gpr[ra+i], gpr[rb])
+        log("sv_maxss test", i, gpr[ra + i], gpr[rb], CR[0], int(CR[0]))
+        gpr[rt] = gpr[ra+i] if CR[0].lt else gpr[rb]
+        if not CR[0].gt:
+            break
+        i += 1
+    return i # new VL
+
+# this version is more akin to SVP64, using an implementation of sv.minmax
+def m3(a):
+    m = 0;
+    nm = 0;
+    i = 0;
+    n = len(a)
+    vl = 4
+
+    while (i<n):
+        while (i<n and a[i]<=m) :
+            print("%d idx %d <= m %d" % ( i, a[i], m))
+            i += 1
+        while  (i < n and a[i] > m) :
+            print("%d idx %d > m %d" % (i, a[i], m))
+            m = a[i]
+            nm = i
+            i += 1
+    return nm;
+
 # /*Testbench*/
 
 test_data = [
@@ -35,3 +67,14 @@ if __name__ == '__main__':
         result = m2(arr)
         print("Index of the maximum value in an array is: %d" % result)
         assert (result == expected)
+
+    # test m2 against m3
+    for i in range(200):
+        array_len = randint(2, 15)
+        array = []
+        for j in range(array_len):
+            array.append(randint(0, 20))
+        print("randomised search list", array)
+        expected = m2(array)
+        print("Index of the maximum value in an array is: %d" % expected)
+        assert (m3(array) == expected)
-- 
2.30.2